Update README.md

README.md

@@ -228,6 +228,24 @@ Would you like to create your own Custom Runtime widget? Please refer our [Demo
 ## Troubleshooting
 
  ### Application Builder 2.0.0 and later
+
+ * **Persistent 'Under Maintenance' Warning Despite Upgrade to Application Builder 2.0:**
+ Typically, users should encounter this warning during the upgrade procedure, although its presence should be brief – lasting no more than a few minutes. If this warning persists even after the upgrade has finished, it indicates a potential issue during plugin installation or may be connected to network-related problems.
+To address this issue, you can follow these steps:
+
+ **Note**: You may need to install your widgets/plugins manually from widget catalog or from administration after following these steps.
+
+
+  1. Logout from Application Builder Application.
+  2. Login again to cumulocity and navigate to Administration -> Ecosystem -> All Applications
+  3. Select Application Builder (custom) and delete it.
+  4. Click on Add Application
+  5. Install Application Builder 2.0 from [here](https://github.com/SoftwareAG/cumulocity-app-builder/releases)
+  6. Logout from Administration
+  7. Login again to cumulocity and navigate to Application Builder
+  8. Application Builder 2.0 will commence the installation process.
+
+  If the problem continues to persist, please don't hesitate to reach out to us for assistance using [Software AG Tech Community](https://tech.forums.softwareag.com/tag/Cumulocity-IoT).
 
  * **Widget/plugins are not installed after upgrade:**
  There are multiple reasons that your widgets/plugins might not installed such as browser page refreshed, network error, etc.